This is far from finished, but I think most players agree we could use a little more war.
But we don't want to add more stupid game mechanics to force war, or the only thing we end up with is tons of fake wars.
The other problem I am trying to solve is that so many wars are until one realm is destroyed.
So here is a rough outline of an idea to promote more, limited wars: Challenges to honour and escalation of conflict.
The rough idea is that players can "challenge" each other in a subtle way, i.e. the challenged one doesn't know what the challenge is for. A challenge is accompanied by a message. The challenged then sets his own stake, hidden again.
The game mechanics would be a condition that needs to happen.
Basically, both parties have bet something. Now the conflict escalates as both parties try to push or trick each other into fulfilling the condition. Whoever succeeds first wins something (prestige, honour, whatever) while the loser loses some.
You can also back out of a challenge, at some cost, and they would have to have a time limit, depending on large the challenge.
Challenges can be lots of things - the other changes realm, disbands his unit, loses his region, etc. etc. - the important thing is that it's not something he profits from and that you can not do to him without overcoming resistance (e.g. If you are the judge, change of realms would not be a challenge because you can ban).
It's a very rough idea, so please don't get lost in the details at this point. He important elements are messages/role play, hidden stakes and escalation of conflict.